Current studies concentrate on comprehensive tests of hypothalamic-pituitary function and on the measurement and administration of specific behaviorally active peptides or peptide analogs. Major findings this year are: There is a significant reduction in cerebrospinal fluid (CSF) oxytocin in drug free bipolar patients in the depressed, manic, and recovered states. CSF vasopressin is significantly lower in drug free psychotic schizophrenic patients compared to controls. Des-amino-8-d-arginine vasopressing (DDAVP), a vasopressin analog, enhances specific components of information processing in patients with Alzheimer's disease analogous to its previously demonstrated effects in depressed patients and controls. In studies of AVP function in anorexia nervosa patients studied while chronically underweight and at intervals following weight gain, we note that not only do many show evidence of partial neurogenic diabetes insipidus, but many also show a previously undescribed syndrome of completely disrupted osmoregulation, which, when present, is consistently associated with marked abnormalities in CSF AVP. Zimelidine increases both CSF AVP and the plasma AVP response to hypertonic saline, compatible with findings in anorexia nervosa indicating common regulatory mechanisms for CSF and plasma AVP.